High temperature superconductor is an unconventional superconductor which cannot be explained by conventional BCS theory. In 1986, Muler and Bednorz firstly discovered cuprate high-temperature superconductors. In 2008, physicists in Japan firstly discovered iron-based high-temperature superconductors. This provides a new system for studying mechanism of superconductivity and gives inspiration to explore other high-temperature superconducting materials.
The iron-based high-temperature superconductors and cuprate high-temperature superconductors have some resemblances in structure. All of them own layered heterostructurs with one conducting layer sandwiched between two insulating layers.
In addition, high temperature superconducting materials usually are synthetized by high temperature reaction, single crystalline or polycrystalline. However, bulk materials are known to suffer from great fluctuations in stoichiometry, disorder, and clustering pathologies with many defects and impurities. At present, iron-based high-temperature superconducting films can be prepared by Pulsed Laser Deposition (PLD). However, these iron-based high-temperature superconducting films usually comprise inhomogeneous structure and many impurities, which may affect studying the mechanism of high-temperature superconductivity.
What is needed, therefore, is to provide a high-temperature superconducting film which can overcome the shortcomings as described above.